A semiconductor element of this invention includes a drift layer of a first conductivity type formed on a semiconductor substrate of the first conductivity type, a well layer of a second conductivity type selectively formed in the surface of the drift layer, a source layer of the first conductivity type selectively formed in the surface of the well layer, a trench formed to reach at least the inside of the drift layer from the surface of the source layer through the well layer, a buried electrode formed in the trench through a first insulating film, and a control electrode formed on the drift layer, the well layer, and the source layer through a second insulating film.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A semiconductor element comprising: a semiconductor substrate of a first conductivity type having a first major surface and a second major surface opposing the first major surface; a drift layer of the first conductivity type formed on the first major surface of said semiconductor substrate; a well layer of a second conductivity type selectively formed in a upper surface of said drift layer; a source layer of the first conductivity type selectively formed in a upper surface of said well layer; a trench formed to reach an inside of said semiconductor substrate from an upper surface of said source layer through said well layer and said drift layer; a buried electrode formed in said trench through a first insulating film; a control electrode formed on the uppermost surface of said drift layer, and the uppermost surface of said well layer through a second insulating film; a first main electrode formed on the second major surface of said semiconductor substrate; and a second main electrode connected to said source layer and said well layer, a part of the first insulating film being formed between an upper surface of the buried electrode and a bottom surface of the second main electrode and being directly contacted with the bottom surface of the second main electrode.
2. An element according to claim 1 , wherein said first insulating film has a thickness larger than a value obtained by multiplying a static breakdown voltage of said element by 20 Å/V.
3. An element according to claim 1 , wherein said first insulating film is thicker than the second insulating film.
4. An element according to claim 1 , wherein an impurity concentration of said drift layer gradually increases toward said semiconductor substrate.
5. An element according to claim 1 , wherein an impurity concentration of said drift layer increases toward a side wall of said trench.
6. An element according to claim 1 , wherein said buried electrode is electrically connected to said first main electrode.
7. An element according to claim 1 , wherein said buried electrode is electrically isolated from said second main electrode.
8. An element according to claim 1 , wherein a bottom surface of said buried electrode is located inside of said semiconductor substrate.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
December 5, 2005
May 12, 2009
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.